A lot of people have been throwing a lot of cold water lately on the notion of Miami as a high-tech “Silicon Beach.” Even Miami Beach Mayor Philip Levine this year called it “the dumbest idea in the world.” Levine’s remark wasn’t all that bright, either. But on the eve of Miami’s first annual eMerge Americas conference – the week-long event starts Friday at various sites throughout the county and is expected to draw more than 3,000 visitors – it’s actually not a dumb idea to take two steps back